As any radio enthusiast in the U.S. knows, for years Radio Shack was the place to buy radios if you were into long distance radio listening. Most of their radios were very good performers for the money and they usually had more than one model to choose from. Before the 1990's many of Radio Shack's radios were custom made in Taiwan and Japan. Around 1989-90 they began to carry Sangean radios, and placed the "Realistic" badge on the front.
The DX-370 radio, tuned to KFNQ 1090, a local Seattle area sports station that carries the CBS Sports Radio network.
The
Realistic DX-375 is unique, in that at first look isn't clear whether the radio is a Sangean or not. It looks like a Sangean radio, with its build quality and the slightly rounded case in front of the speaker (similar to the Sangean ATS-800A). However, unlike many other Radio Shack portable radio models, the DX-375 was
not a re-badged, popular Sangean radio available elsewhere under the Sangean name. For a long time, it was a mystery sourced radio.There are some DXers online who claimed this radio was possibly built by Tecsun, a well known Chinese radio brand.
However, internal evidence (as well as an email back from Sangean) shows that that DX-375 is a Sangean radio.
IT'S A SANGEAN RADIO -- MS-305A
I've taken the back off my DX-375 twice, to hit the volume control with some lube. The second time I had the back and front off, I looked over the radio and took pictures. I noticed it had a large MW loopstick, and I also noticed the factory model number, which is clearly seen underneath the speaker cut-out.As shown below, the PCB on my DX-375 says 20-212 (the Radio Shack catalog number) and "MS-305A", which is apparently a factory model number. The "MS-" prefix is a Sangean radio prefix (a Google search brings up a Sangean MS-112, MS-101, and MS-103L). So the MS- number is evidence that this radio was custom built by Sangean for Radio Shack. Other factors, including similarities in the circuitry of this radio to the Sangean ATS-305 (same IF chip, same coverage, same switching transistors, similar PCB#, similar RF amp transistor used in the SW-MW chain, etc.), also hint that the DX-375 was made by Sangean.
SANGEAN CONFIRMS THE DX-375 IS A SANGEAN RADIO
After suspecting that the DX-375 was a Sangean radio, I emailed Sangean. I described the radio, told them about the "MS-305A" model number on the PCB, and sent them some pictures, both of the inside and outside of the DX-375.
They confirmed that yes, the DX-375 is indeed a Sangean radio.
When the DX-375 first came out, it had the traditional "Realistic" brand name on its front. Some time before they quit selling this radio, Radio Shack started branding the DX-375 with the less classic-looking "Radio Shack" badge on the front of it. Presumably, the guts and perfomance of the radio were identical (this was during a time other radios, like the DX-390 and 392, were also being re-badged).
The radio is made in China, and has good build quality.
If you're in a low signals area (as I am), it will help to add a length of wire to the whip antenna to boost signals to the radio. I use a 25 ft. indoor wire (about 7-8 meters), which I attach to the whip with an alligator clip. It makes it easier to use the DX-375 because I can tune across a SW band more quickly and keep an eye on the red LED tuning indicator to check for SW stations. In a high signals area, using the the whip might work O.K.
Because of the tuning lag, I usually use the DX-375 on SW by tuning to several stations I already know by heart: 5025 khz Rebelde, 11780 khz and 6180 khz Radiobras, 6160 khz CKZU Canada, etc. I generally tune into those stations by directly entering their frequencies using the buttons on the front of the radio. I also will program stations into the 10 SW memories and listen that way. Sometimes I'll tune around and keep an eye on the red LED indicator. But mostly if I bandscan the SW, I'll use a different radio (usually my DX-370 or Grundig G2).
If it seems to be a good night for SW I'll go ahead and tune across the 49 meter band, which is the most crowded SW band here in the NW, especially in the morning when Asia comes in. With some stations, the internal loop (designed to receive SW as high as 7.3 Mhz) will bring the stations in. One morning I heard the China Radio Russian station coming in just off the loopstick, which was cool. I've also nulled out Radio Rebelde on 5025 khz with it.
On MW it sounds like the bandwidth is around 6-7 khz wide, but it's adequate for separating a weak station from a nearby local station.
There is a tone switch on the side of the radio to reduce the treble which helps reduce some splatter on the AM and SW bands, as well as smooth out the highs on FM when listening through the speaker. There is a "DX-Local" switch on the other side of the radio that I never have used. The radio has a 3V in jack, for a plug from an AC adapter, but the radio does so well on C Cells an AC adapter really isn't needed.
The only negative sound-wise with this radio is that the AM band could use a bit more bass response through headphones. There is apparently a 'bass cut' adjustment off the IF chip somewhere and in my view that bass cut isn't needed. It still sounds good -- I just prefer a bit more bass response on AM when DXing.
The DX-375's AGC (Audio Gain Control) is just about right -- low signals are increased in volume and loud stations don't blast your eardrums once you tune into them. Unlike a couple of Radio Shack's more popular digital portables (like the DX-398 and DX-390, also made by Sangean) the AGC doesn't pump; and overall sound through headphones is good enough for DXing for longer periods.
The DX-375 has a decent, full sound through the speaker on AM, and an even fuller sound through the speaker on FM. Through headphones the radio isn't midrangy or shrill like some DX radios -- it is smooth sounding audio, with a much better sound than the more expensive DX-398 on headphones. There is no listener's fatigue with a DX-375.
A closer look at the back of the DX-375's PCB, showing the "MS-305A" factory model number at top, the thickness of the loopstick, and the TA8132 IF chip, which is the small chip in the center of the pic.
The
DX-375 tunes the SW bands, receives FM in stereo (there is only one
speaker, but FM is in stereo through the headphone jack) and also
receives the MW/AM band. It is decent on SW, as long as you direct tune
with the keypad, as scan tuning is a bit tedious (as will be described later here). It has decent sensitivity off the whip antenna on SW.The radio is made in China, and has good build quality.
A diagram showing some of the Sangean ATS-305's components, showing the RF transistor serving MW as well as SW. The IF chip, TA8132 (same as used in the DX-375) can be seen to the right of the RF transistor. It's possible the RF section of the DX-375 is a similar design to that shown on this diagram.
SHORTWAVE PERFORMANCE -- GOOD OFF THE WHIP, SLOW BANDSCAN TUNING
The DX-375 has good sensitivity off the whip on Shortwave, and is a good performer with one drawback: the tuning across the band is slow. When tuning across a SW band you have about a one second lag between channels. If you're in a high signals area, you can watch the red tuning LED and it will immediately tell you if there is a strong signal even if you can't hear it yet because of the muting (see below).If you're in a low signals area (as I am), it will help to add a length of wire to the whip antenna to boost signals to the radio. I use a 25 ft. indoor wire (about 7-8 meters), which I attach to the whip with an alligator clip. It makes it easier to use the DX-375 because I can tune across a SW band more quickly and keep an eye on the red LED tuning indicator to check for SW stations. In a high signals area, using the the whip might work O.K.
Because of the tuning lag, I usually use the DX-375 on SW by tuning to several stations I already know by heart: 5025 khz Rebelde, 11780 khz and 6180 khz Radiobras, 6160 khz CKZU Canada, etc. I generally tune into those stations by directly entering their frequencies using the buttons on the front of the radio. I also will program stations into the 10 SW memories and listen that way. Sometimes I'll tune around and keep an eye on the red LED indicator. But mostly if I bandscan the SW, I'll use a different radio (usually my DX-370 or Grundig G2).
If it seems to be a good night for SW I'll go ahead and tune across the 49 meter band, which is the most crowded SW band here in the NW, especially in the morning when Asia comes in. With some stations, the internal loop (designed to receive SW as high as 7.3 Mhz) will bring the stations in. One morning I heard the China Radio Russian station coming in just off the loopstick, which was cool. I've also nulled out Radio Rebelde on 5025 khz with it.
THE DX-375 REALLY SHINES ON MW
Although it works well on FM and SW, it is on MW/AM where the DX-375 radio really shines. It has really good sensitivity for a non-TRF portable, and the
selectivity is good enough for DXing. When I A-B it with a Superadio II the DX-375 sounds like it's about 1 db or so weaker on very weak DX channels (depending on how good conditions are. PS -- I live in a low signals area). The DX-375 doesn't have a tuned RF stage and 200 mm loopstick like an SRII has, but considering its circuitry and antenna, the DX-375 is an excellent performer. I usually use mine with an external loop -- which I do with all my radios, including the SRII and PR-D5 (when needed).On MW it sounds like the bandwidth is around 6-7 khz wide, but it's adequate for separating a weak station from a nearby local station.
There is a tone switch on the side of the radio to reduce the treble which helps reduce some splatter on the AM and SW bands, as well as smooth out the highs on FM when listening through the speaker. There is a "DX-Local" switch on the other side of the radio that I never have used. The radio has a 3V in jack, for a plug from an AC adapter, but the radio does so well on C Cells an AC adapter really isn't needed.
The only negative sound-wise with this radio is that the AM band could use a bit more bass response through headphones. There is apparently a 'bass cut' adjustment off the IF chip somewhere and in my view that bass cut isn't needed. It still sounds good -- I just prefer a bit more bass response on AM when DXing.
The DX-375's AGC (Audio Gain Control) is just about right -- low signals are increased in volume and loud stations don't blast your eardrums once you tune into them. Unlike a couple of Radio Shack's more popular digital portables (like the DX-398 and DX-390, also made by Sangean) the AGC doesn't pump; and overall sound through headphones is good enough for DXing for longer periods.
The DX-375 has a decent, full sound through the speaker on AM, and an even fuller sound through the speaker on FM. Through headphones the radio isn't midrangy or shrill like some DX radios -- it is smooth sounding audio, with a much better sound than the more expensive DX-398 on headphones. There is no listener's fatigue with a DX-375.
The DX-375 picking up Radio Rebelde on 5025 khz using just its internal ferrite loopstick antenna. As you can see, it is receiving Rebelde strong enough to light up the tuning signal LED -- the DX-370 below, which is not designed to receive SW on its loopstick, is receiving the station but extremely weak -- it's not even triggering the DX-370's LCD tuning indicator. I've found that the DX-375's loopstick -- used with or without the whip antenna -- can in some cases reduce RFI on SW -- but not by much. Household RFI is just too powerful for the vast majority of SW listening.
TUNING LAG, BUT THERE IS A WORKAROUND
If you tune with the up and down buttons
there is almost a one second lag in tuning steps (due to muting), which
makes it a bit time consuming when you want to scan through a SW band --
it's not so much of a problem on the MW band or FM band, where there are many more
signals.
If
you 'auto-search' on SW (press an up or down button and hold it) the
radio will sometimes skip over audible stations instead of stopping on
them, because the SW station's strength may not be above the radio's
search threshhold. If you press the up or down key repeatedly, you can
toggle through the channels, but on some SW bands that can be time consuming.
DURING AUTO-SCAN, OR TOGGLING UP THE BAND, WATCH THE RED LED
But because the tuning increment works slowly (about a second), it's best to watch the red LED indicator, because the LED indicator will light up on stations that don't stop the auto-tuning, and it will also light up before the sound breaks through the muting. On AM the DX-375 is very good, coming surprisingly close to a Superadio in performance (maybe 1 db weaker on weak MW channels), considering it has a shorter, smaller loopstick antenna and isn't a TRF design. It's good because the IF chip is high gain and the radio has a very good loopstick antenna (140mm x 9 or 10mm -- the thickness is hard to measure accurately, but it's over 8 mm), which is large for a portable. I believe the loopstick is larger than the one used in most of the Sangean 800- and 900-series SW radios
The
slow tuning of this radio isn't as big a deal on the MW/AM band because
usually every channel has a station on it, and most times I just use
the keypad if I want to jump up the band. And usually when tuning the MW
band I listen to each channel to see what's on, anyway.
The DX-375 has a TA8132 IF chip, which is a fairly high gain chip, which also adds to the radio's performance. Although I can't find a schematic for this radio anywhere online, the similar ATS-305 has an FET in the SW-MW IF chain, and there are a couple FET's in the DX-375's parts list. So it's probable that an FET in the IF amp chain adds to the DX-375's performance on the MW band.
It has an FM RF/IF front end chip (TA7358) but it doesn't quite pull in FM stations as strongly as my Realistic DX-370. I don't know why that is -- technically, there shouldn't be much of a difference.
The DX-375 has a TA8132 IF chip, which is a fairly high gain chip, which also adds to the radio's performance. Although I can't find a schematic for this radio anywhere online, the similar ATS-305 has an FET in the SW-MW IF chain, and there are a couple FET's in the DX-375's parts list. So it's probable that an FET in the IF amp chain adds to the DX-375's performance on the MW band.
It has an FM RF/IF front end chip (TA7358) but it doesn't quite pull in FM stations as strongly as my Realistic DX-370. I don't know why that is -- technically, there shouldn't be much of a difference.
A plastic shim inside the back cover of the battery compartment can help extend the life of C Cells in a DX-375. The spongy material breaks down over time, and sometimes isn't sufficient enough to keep the batteries tight in place. The plastic shim I made from the top of a protein shake bottle can be seen inside the battery cover in the picture above.
USE A PLASTIC OR CARDBOARD SHIM IN THE BATTERY COMPARTMENT TO GET MORE OUT OF YOUR BATTERIES
The DX-375 runs on two C batteries, and they last a reasonably long time.
I've had decent results with heavy duty batteries, especially if I use
headphones. The batteries last a while because the radio has no clock,
so when the radio is 'OFF', it's actually OFF! (well -- there still is a
tiny bit of current drain to run the power switch -- but you get the
idea!). The low battery indicator will come on when the radio hits
around 2.0-2.4 volts, then -- after a bit -- the radio simply cuts off.
The batteries last longer on MW/AM than they do on FM or SW (according to the specifications the radio uses about 25% less power on the MW band). I have noticed that when the batteries get down around 2.4 V or so the battery indicator will flash on SW and FM, but the radio will still operate normally on MW for a while longer.
I usually can tell when the batteries are lower than 3 volts because after a while I'll have to press the power switch two times to switch on the radio. It's been that way since the radio was new. This happened a lot more often before I discovered the benefits of adding a plastic shim beneath the battery compartment cover, which presses the C cells together better.
Batteries will last longer in the radio with the plastic shim in the battery compartment. I've found that the battery compartment is larger in diameter than some brands of C cell batteries. Consequently, without a shim, the battery indicator may come on earlier than necessary, and you can possibly get lower battery life because of it.
I cut a shim from the lid to a big plastic bottle, and then shoved it in between the batteries and the battery compartment cover. C Cells last longer in my DX-375 now. I still have to press the power button more than once when the batteries are weak, but not as much as I used to. And I get longer battery life with the shim, than without.
The batteries last longer on MW/AM than they do on FM or SW (according to the specifications the radio uses about 25% less power on the MW band). I have noticed that when the batteries get down around 2.4 V or so the battery indicator will flash on SW and FM, but the radio will still operate normally on MW for a while longer.
I usually can tell when the batteries are lower than 3 volts because after a while I'll have to press the power switch two times to switch on the radio. It's been that way since the radio was new. This happened a lot more often before I discovered the benefits of adding a plastic shim beneath the battery compartment cover, which presses the C cells together better.
Batteries will last longer in the radio with the plastic shim in the battery compartment. I've found that the battery compartment is larger in diameter than some brands of C cell batteries. Consequently, without a shim, the battery indicator may come on earlier than necessary, and you can possibly get lower battery life because of it.
I cut a shim from the lid to a big plastic bottle, and then shoved it in between the batteries and the battery compartment cover. C Cells last longer in my DX-375 now. I still have to press the power button more than once when the batteries are weak, but not as much as I used to. And I get longer battery life with the shim, than without.
OTHER PECULIARITIES
Sometimes
I get an image on the DX-375 high up in the MW band, and sometimes another one in the low band -- but they're not
always there. They don't get in the way of DXing with the radio, though.
The
only 'maintenance' I've had to do with my DX-375 was squirting some DeOxit
into the volume control. There is a convenient, very small hole near
the side of the radio's PCB that allows for you to squirt some lube into
the control -- if you take the back off the radio.
The
DX-375 with the back off. The loopstick is fairly large, as can be seen
(along the top side of the radio). The tiny hole that makes it easy to
lube the volume control is near volume control's upper right solder pad
in this picture (hard to see ). Whether the hole is intended to be there
or not, I don't know -- but it works.
You can also
squirt lube with the radio's back case left on, by squirting it down the
side of the volume control knob, but not all of it will get inside the
control where it's more useful.
The
only glitch with this radio is on rare occasions the microprocessor can
apparently wig out. You reset it by taking the batteries out and
putting them back in a few minutes (or even a half hour) later. I've had
mine for over a decade and the radio's never wigged. So this problem is fairly uncommon.
The
DX-375 has built in back-to-back diode protection for the whip antenna
(the diodes are on the component side of the PCB, near the FM RF amp
chip) which means if you happen to touch the radio with a static charge
in Winter, it probably won't zap the RF amp transistors.
The memories are extremely easy to program, and work quickly. It has a 'memory scan' feature in which the radio will search through each memory location and stop when it 'sees' a strong enough signal. I've never used this feature, but I can see where it could be useful with SW, and maybe even with MW. Once again, the red LED will light up long before the scan stops on a channel.
The buttons
on the DX-375 have a positive feel, and the radio is well built. Mine
took a dive to the floor within a year after I got the radio; the dive
left a small dent in the whip antenna -- the radio has worked fine ever
since.
The memories are extremely easy to program, and work quickly. It has a 'memory scan' feature in which the radio will search through each memory location and stop when it 'sees' a strong enough signal. I've never used this feature, but I can see where it could be useful with SW, and maybe even with MW. Once again, the red LED will light up long before the scan stops on a channel.
The DX-375 with the front off. The buttons are discrete buttons, similar to those used in some Panasonic radios -- as can clearly be seen in this pic. They have an excellent tactile feel to them.
A GOOD DXer, POSSIBLY A DECENT PREPAREDNESS RADIO, TOO
If you happen to find a
DX-375, they are excellent for MW DXing and pretty good for SW listening, and FM is in
stereo through the headphones, which is always a plus. :-)Although the DX-375 doesn't have the extended battery life of a GE Superadio, Sony SRF-59 or Sony ICF-38, it has better battery life than other digital SW radios, like the DX-398 and more recent Radio Shack ATS-505/200-629 World Receiver (both of those are good radios, but both of those radios eat batteries). A set of two C cells is relatively cheap and they will last a couple weeks or more in a DX-375 depending on how much it is used. And, naturally, if you use headphones, the batteries will last much longer.
For emergency preparedness I'd choose a DX-375 over a Grundig G2, Tecsun or other recent model radio that has a rechargeable battery, as there is little you can do when the power is out for an extended period when rechargeables go dead (unless you charge them in your car, which can apparently be done, if you want to run your car's battery that long. My G2 takes 4-5 hours to charge from the AC adapter). C Cells are easy to pack away in a drawer or closet, and are relatively cheap.
NO LONGER IN PRODUCTION, BUT AVAILABLE USED ONLINE
The DX-375 is no longer made, they are available on the used market, and I've seen them for as low as $40 on auction sites online.A lot of DXers might even have one of these radios around and haven't thought about using one to DX the MW band with. If you have a DX-375 and are into MW distance listening, they're definitely worth trying out. Place an external loop next to one and it will give a Superadio a run for the money.
Thanks for taking the time to provide this interesting information on the DX 375. Great detective work!!
ReplyDeleteNo prob, man. It was an interesting challenge. I kept hearing online that the DX-375 was made by Tecsun. Now we know differently. It's surprising Sangean didn't market their own version, but it kind of makes the DX-375 more special -- the last unique, Realistic-branded SW radio. I still DX with mine many nights and mornings. Peace. Chris
DeleteHey there. Is there any chance you know which ac adaptor works with this radio? I have one of these and of course it works on batteries, but I'd love to have an ac adaptor for it. Thanks
ReplyDeleteHi Islamoradasteve. I don't know off-hand, but it would have to be 3 Volts DC, center pin negative. I've seen some online after doing a search.... You'd want an old style one that had an actual transformer, as the modern switching power supplies put out a lot of radio noise. I'd just stay with batteries... That's all I've used in my DX-375 since I got it. I don't think I have ever used an adaptor for it... Peace and good DX. Chris
Deletewhere can i purchase a replacement antenna for Dx-375?
ReplyDeleteHi Unknown,
ReplyDeleteI really do not know offhand. I would buy one that would fit a modern Tecsun or Grundig -- the dimensions might be close enough. I'm sure there are replacements available for those radios. You may just want to search for 'portable radio whip antenna' on a search engine. Radio Shack obviously no longer services the DX-375, and I'm not sure Sangean makes parts for them anymore.
I've fit replacement whip antennas to boomboxes in the past... I had to file the slot in the replacement whip a little to make it fit the stub on the boombox, but it worked.
Thanks for taking time to read and comment on my blog, and hope you can get your DX-375 in prime shape again. :-)
Chris
What is an external loop?
ReplyDeleteHi Unknown. An "external loop" is a loop antenna, made for MW/AM band reception only, that you set next to your radio to boost your reception. If you search for "Eton AN-200" on the internet it will probably show you a picture of one.
DeleteExternal loops are basically loops of wire in a plastic enclosure, with a tuner attached, which tunes the loop for maximum signal. You set the external loop next to your MW/AM radio -- no cable or connector is necessary. The radio picks up the signals off of the external loop through induction.
The external loop boosts the signal when you tune the external antenna using its tuner knob. It can be a little tricky at times, but you usually will hear the radio station 'peak' in volume, especially on a PLL chipped radio like the DX-375.
With the new DSP chipped radios that are popular today (like a lot of Tecsuns and Sangeans), the signal doesn't always peak in *volume*, but you will hear the station itself a lot more clearly. For DXing, even a very good DXer like a DX-375 can pull in a few more signals with an external loop, especially if you live in a valley, like I do. External loops (like the Eton AN-200, which I have) aren't too expensive. Maybe $30-$50 US.
I hope this helps. And thanks for checking out my blog -- and keep on listening to your DX-375. :-) They are great radios.
Chris
I bought the dx-375 at a thrift store, best thing I ever found! I noticed a problem that started happening recently where when switched on the lcd screen would be completely lit up and the buttons would not work. If I take the batteries out for awhile then back in it would work again. Is this an issue that's known about or is there anything I should do or know about? Thanks.
ReplyDeleteHi Anonymous. What you describe is the radio needing a 're-set', which you can do by taking batteries out of a radio (and unplugging any other power, like a wall-wart AC adapter), and wait for maybe 15 to 20 seconds. Then plug the batteries back in. It resets the microprocessor. This is standard procedure for a lot of radios. The microprocessor, naturally, runs on firmware, and sometimes it just wigs. Usually it's pretty rare. Often, it will happen if the radio hasn't been used in over a year or two. When I first fired up my DX-440 after it sitting in the closet for maybe 6-7 years, it wigged a couple times until I ran it for an hour or two. It's worked normally since. Radio seem to like to be played. :-)
DeleteIf this is happening more frequently on your DX-375, it's also possible that your batteries are getting weak, and sometimes when the DX-375 sees weak batteries, the power button in particular only responds when you hit it 2-3 times or so. I've had that happen in my DX-375 since I bought it in the mid 1990s. The solution I finally used was to cut a piece of plastic and use it in the battery compartment as a shim, to hold the batteries more firmly in the battery compartment, so they don't jostle and cut power even for a millisecond or so.
When SW radios see low power, their microprocessors can wig. I had this happen to my Grundig G2 recently.
Normally, your 375 shouldn't wig out very frequently. That said, you asked me if the wigging is a known issue and it looks like it has been since the DX-375 came out in 1995 or whenever it was introduced. And if yours has wigged a couple times, maybe it's just because it wasn't used for a few years. Just a guess.
When the DX-375 first came out some guys in magazines talked about their DX-375 suddenly becoming non-responsive, and they chalked it up to some sort of static discharge zapping the microprocessor somehow. Maybe the user touched the radio's whip antenna after crossing a carpeted floor, that kind of thing. Mine gets a little finicky if the battery gets low -- have to press the power button 2-3 times to get it to work. Once it's working, I've had no problems. I fixed most of my 375's power-on problems with the plastic shim in the battery compartment.
My suggestion: try new heavy duty or alkaline batteries. Find a plastic lid or something like that and cut a small rectangle of plastic and press it against the batteries before shutting the battery compartment. It doesn't have to be so think the battery door is hard to shut -- just enough to keep the C-Cells from jostling, which can cause power issues when they get weak. See if that helps.
Thank you for your comment, and I hope your DX-375 works more normally for you in the future.... They're awesome MW/AM radios. Thanks for checking in and reading the blog. Peace.
Chris
.....I'll also add that sometimes taking batteries out and waiting a half hour or so works in re-setting some radios. My Fuji camera locked up on me when the batteries got low. It was in the desk drawer for several years. That's how long it took for it to re-set (there is an article about that on this blog). So, sometimes wait a while, then replug in the batteries.
DeleteChris
Hello. My wires, the yellow positive and black negative wires came off of the attachment on the speaker. Are they soldered or just wrapped around the metal leads? I am new at this so I may not be using the correct vocabulary. You can see this on the 8th picture above. Thank you. Vicky vickyhoward@sbcglobal.net
ReplyDeleteHi Vicky, first off -- sorry for the late reply. My internet service has been a bit spotty over the past week.
DeleteAs for your question: I believe that the wires are soldered onto the speaker terminals. I have not had a chance to take the back off my DX-375 to double check this since I saw your question, but from looking at the pic, and from memory, I am at least 99.9% certain that the wires are soldered on to the speaker terminals. Just wrapping them around the terminals / metal leads would not be a great idea, as the vibrations from the speaker, moving the radio, etc., would cause electrical noise. So re-attach them with a bit of solder, using a soldering iron or soldering gun -- that probably is best.
Thank you for your question, and thank you for reading my blog. Enjoy your DX-375!
Any more questions, feel free to ask. I'm no expert, obviously, but I'll always at least try to lead folks in the right direction if they've got questions about these radios. :-)
Peace,
Chris
Mark
ReplyDeleteHi Mark. Thank you for your comment and question. First off, the DX-375 is terrific on battery usage, so my own preference is to just use C-Cells as they're not prohibitively expensive, and they work a long time in the DX-375 -- even longer if you use headphones a lot while DXing with it.
ReplyDeleteAs for an adaptor, it would have to be 3 Volts, with a pin that fits the adaptor jack, CENTER PIN NEGATIVE. I'm not sure where there are any available online. I just looked, with no success. One caveat -- any new, switching style power supply -- and those are the only kinds you can get new anymore, due to US government fiat -- would cause a lot of RFI interference on the MW band.
The modern 'switching' style supplies use electronics to turn the AC from the wall into DC, and it can cause noise on AM and Shortwave. The old school iron core supplies were silent, for the most part. But they ate more power out of the wall, so the US Government deemed them non-eco friendly.
Sangean has managed to remedy this with their new switching power supplies, but I don't know if they make one that's 3 Volts, Center Pin Negative. I have looked at their own website, and they only seem to sell supplies for their newer radios, which are all 6 volts or 9 volts, and some of them have reversed polarity compared to their older radios, and sometimes they are AC to AC adaptors, which wouldn't work on older Sangean made radios like the DX-375.
I would just use the C Cells, and/or get a charger for some rechargeable C Cells, and use them.
Like I said, a set of 2 C Cells in a DX-375 last a long time. As the batteries weaken a bit you might have to press the power button twice, which is normal. Putting a small plastic shim in the battery compartment between the batteries and the compartment door/cover also extends battery life. Good luck. And than you for checking in and checking out my blog.
Chris
PS, Mark -- I wanted to add that I also do not personally have an AC supply for my own DX-375. I never got one. One didn't come with the radio, although I am sure that some suitable AC adaptors were sold at Radio Shack for the DX-375.
ReplyDeleteThe DC input jack on the side of the radio is smaller in size than the DC input jack in other Sangean portables that Radio Shack sold in the 1990s. So I don't think that the DX-375's AC adaptor was very common. This is one reason I advise DX-375 owners to just use the C Cell batteries, and/or maybe some rechargeables. Thankfully, the radio lasts a long time on batteries, as it has no functions (like a clock, or an alarm) eating up juice when the radio is turned off.
The only think eating power when the radio is turned off is the tiny amount of power used by the microprocessor to 'look' at the power button.
I hope this all helps you, and others, who are wondering about AC adaptors for the DX-375.
Peace,
Chris
'thing', not "think", woops. Typos......
ReplyDeleteHi, very informative article on the DX-375. I got mine at a second hand store complete with depleted, but not leaky, batteries and a broken antenna, $8.00. Canadian currency! It did have the “push ON repeatedly” problem, new batteries rectified that as you know. I jury rigged a 35 feet long wire antenna across the ceiling and “alligatorized” it to the antenna stump but results were disappointing to say the least. Your comments above about rfi in the house are bang on, which is confirmed by the multiple authors of the ARRL RFI BOOK…. An antenna tuner (VS-300A) did not help much until I Earth grounded both the tuner and the ‘375 (via the earphone outer metal nut). But even then, results on SW are disappointing.
ReplyDeleteIt occurs to me now that I have read most articles of the RFI book and your article, that having the antennas, MW loop and FM/SW single wire extension outside would go a long way in improving my results.
This said, I must ask, how long is the extended FM antenna? I would like to be able to do comparative field check…
Thanks again for the very good article and all the answer to the other readers, well done.
Hi Anonymous! Thank you for your kind comments about the DX-375 article, it's much appreciated. $8 Canadian is a great price for such a good radio! I just measured the whip antenna on my DX-375 and from the top of the swivel mount to the tip it is 26 and 3/4 inches / 680 mm.
DeleteWhen I clip my 25+ ft indoor wire to my DX-375's whip, I get much better SW reception, but it's not particularly mind blowing. It doesn't seem to help FM much, though. I think the radio was made for higher SW signals areas than the remote PNW US. On MW, however, as I say in my article, it's a much different story. A longer antenna for SW (like the outdoor one you suggest) probably would do OK. I am not certain that the DX-375 would overload like some radios do. I never tried my 100 foot outdoor antenna with my DX-375 when I still had that antenna (it blew down some time after 1999 or 2000), so I don't really know how a longer, outdoor antenna would do.
If you get overload the 'proximity effect' method might work -- placing the radio's whip near the feedline, or wrapping a couple turns of feedline around the radio, or a couple loops of feedline near it -- that sort of thing. Being that the 375 gets the lower SW through the loopstick as well as the whip, something like that might work. I used the proximity effect with my DX-370 and got decent results a few times (I heard Radio Tunisia on my 370 that way in 1995 or 1996 or so).
As mentioned, the DX-375's loopstick also works on the low SW ranges, although reception varies. I used to be able to tune in Rebelde on 5025 kHz with the DX-375 off its internal loopstick, and even null the station. But that was in 2012, when conditions were a bit better and Rebelde was on the air more.
Last but not least, if you use headphones with the DX-375, use a decent set with bass response, especially when tuning the MW band. It makes the 375 sound a lot better. I use a $25 US set of Sonys. It's like night and day compared to the less expensive set I had been using for several years previous. The 375 doesn't put out a ton of bass response through the headphone jack. The Sonys really help in that regard.
Thanks for checking out my blog. It's always great to hear from Canada, as my mother was born there (Edmonton). Both sides of my family lived in Canada at various times long before I was born. So I often feel an affinity for your country. Peace, and good DX. Chris
Hi: Great article. Would it be worth fixing a DX-375? I put a universal power in the plug wrong polarity and well radio will not work. So the power supply chips are fried?Before that happened it was a great radio mostly used for FM radio.
ReplyDeleteHi Scott,
DeleteFirst off, does it work on batteries? If it does, a DX-375 will run a LONG time on batteries.
If you can fix it, yes. It's worth it. I reversed the polarity by accident when plugging in an adaptor to my DX-370 (also made by Sangean), and it smoked a diode that was soldered to the adaptor jack. There may be a similar diode in the DX-375. I don't know for sure, as I haven't opened mine up in a few years. But open up the back of your radio, and look at the solder connections around the AC adaptor input jack. If you see something -- a small component -- fried, it might be the diode. Solder a new one in, observing the correct polarity. Then try the radio on batteries only. See if it works.
I think the diode -- at least on the DX-370 -- was to protect the rest of the radio's circuitry from polarity reversals. You can check out my article on the DX-370 and you can see the diode I soldered in. When I had reversed the polarity on my DX-370 by accident, I could smell the electronic smoke from the original diode being fried. Yet my DX-370 still works today after the fix. It's worth a try.
Also, it's probably better to use small portables on batteries rather than wall-warts. The DX-375 and other Radio Shack portables of the 1990s were usually really good on batteries. Even rechargeables are probably a better idea than using a wall wart. I once plugged in the wrong wall-wart into my DX-398 and I'm lucky I didn't fry it -- it's a 6 volt radio and I put a 9 volt adaptor into the jack. I didn't realise my mistake until 5 minutes later. After that, I just use batteries on my portables, and/or really double check on the adaptor I'm using.
Thanks for checking out my article, and good luck with your DX-375.
Chris
PS, the above comment says I'm "Anonymous", but it's actually me, the writer of the Interrock Nation blog.
ReplyDelete